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Oyster Optics, LLC v. Coriant America Inc.

United States District Court, E.D. Texas, Marshall Division

December 5, 2017

OYSTER OPTICS, LLC,
v.
CORIANT AMERICA INC., et al.,

          CLAIM CONSTRUCTION MEMORANDUM AND ORDER

          RODNEY GILSTRAP UNITED STATES DISTRICT JUDGE.

         Before the Court is Plaintiff Oyster Optics LLC's (“Plaintiff's or “Oyster's”) Opening Claim Construction Brief (Dkt. No. 157). Also before the Court are Defendants Cisco Systems, Inc., Fujitsu Network Communications, Inc., Huawei Technologies Co., Ltd., Huawei Technologies USA Inc., Infinera Corporation, Coriant (USA) Inc., Coriant North America, LLC, Coriant Operations, Inc., and Alcatel-Lucent USA Inc.'s (“Defendants'”) Responsive Claim Construction Brief (Dkt. No. 165) and Plaintiffs' reply (Dkt. No. 167).

         The Court held a claim construction hearing on November 20, 2017.

         Table of Contents

         I. BACKGROUND ....................................................................................................................... 3

         II. LEGAL PRINCIPLES ........................................................................................................... 4

         III. AGREED TERMS ................................................................................................................. 8

         IV. DISPUTED TERMS ............................................................................................................ 10

         A. “phase modulate” ................................................................................................................ 10

         B. “output for altering the phase of the phase modulator” ...................................................... 18

         C. “energy level detector” ........................................................................................................ 21

         D. “tap” / “tapping” / “tapped” ................................................................................................ 26

         E. “receiver” ............................................................................................................................. 30

         F. “the optical signals” ............................................................................................................. 36

         G. “line card” ........................................................................................................................... 41

         H. “OTDR” .............................................................................................................................. 44

         I. “arm” and “path” .................................................................................................................. 47

         J. “path length difference” ....................................................................................................... 48

         K. “the second arm being longer than the first arm” ............................................................... 51

         L. “phase compensation circuit” .............................................................................................. 52

         M. “means for phase modulating as a function of an input electronic data stream and a second electronic data stream having a delay, thus creating a phase modulated optical signal with encoded information for recovery” .................................................................. 56

         N. “means for receiving the optical signal from the transporting means” ............................... 61

         V. CONCLUSION ...................................................................................................................... 66

         I. BACKGROUND

         Plaintiff brings suit alleging infringement of United States Patents No. 6, 469, 816 (“the '816 Patent”), 6, 476, 952 (“the '952 Patent”), 6, 594, 055 (“the '055 Patent”), 7, 099, 592 (“the '592 Patent”), 7, 620, 327 (“the '327 Patent”), 8, 374, 511 (“the '511 Patent”), 8, 913, 898 (“the '898 Patent”), and 9, 363, 012 (“the '012 Patent”) (collectively, “the patents-in-suit”). (See Dkt. No. 157, Exs. 1-8.) Plaintiff submits that the patents-in-suit are “generally directed towards systems and methods for transporting information by modulating light waves transmitted and received across transparent optical fibers.” (Dkt. No. 157, at 2.)

         The parties have submitted that the patents-in-suit can be classified into two groups: the “Group 1 Patents” (United States Patents No. 6, 469, 816, 6, 476, 952, 6, 594, 055, and 7, 099, 592); and the “Group 2 Patents” (United States Patents No. 7, 620, 327, 8, 374, 511, 8, 913, 898, and 9, 363, 012). (Dkt. No. 157, at 2; Dkt. No. 165, at 1 n.1.)

         The '816 Patent of Group 1, for example, titled “Phase-Modulated Fiber Optic Telecommunications System, ” issued on October 22, 2002, and bears a filing date of May 24, 2001. The Abstract of the '816 Patent states:

A fiber optic data transmission system has a transmitter having a laser emitting a continuous wave light, a phase modulator phase modulating the continuous wave light so as to create an optical signal bearing information in phase-modulated form, and a telecommunications optical fiber connected to at least one receiver, the phase-modulator being connected to the telecommunications fiber so that the phase-modulated information optical signal is transmitted over the telecommunications fiber without recombining with the continuous wave light.

         The '327 Patent of Group 2, for example, titled “Fiber Optic Telecommunications Card With Energy Level Monitoring, ” issued on November 17, 2009, and bears a filing date of July 3, 2002. The Abstract of the '327 Patent states:

A transceiver card for a telecommunications box for transmitting data over a first optical fiber and receiving data over a second optical fiber. The card has transmitter for transmitting data over the first optical fiber, the transmitter having a laser and a modulator, a fiber output optically connected to the laser for connecting the first optical fiber to the card, a fiber input for connecting the second optical fiber to the card, a receiver optically connected to the fiber input for receiving data from the second optical fiber, and an OTDR optically connected between the transmitter and the fiber output or between the receiver and the fiber input. An energy level detector is also provided between the receiver and the fiber input.

         II. LEGAL PRINCIPLES

         It is understood that “[a] claim in a patent provides the metes and bounds of the right which the patent confers on the patentee to exclude others from making, using or selling the protected invention.” Burke, Inc. v. Bruno Indep. Living Aids, Inc., 183 F.3d 1334, 1340 (Fed. Cir. 1999). Claim construction is clearly an issue of law for the court to decide. Markman v. Westview Instruments, Inc., 52 F.3d 967, 970-71 (Fed. Cir. 1995) (en banc), aff'd, 517 U.S. 370 (1996).

         “In some cases, however, the district court will need to look beyond the patent's intrinsic evidence and to consult extrinsic evidence in order to understand, for example, the background science or the meaning of a term in the relevant art during the relevant time period.” Teva Pharms. USA, Inc. v. Sandoz, Inc., 135 S.Ct. 831, 841 (2015) (citation omitted). “In cases where those subsidiary facts are in dispute, courts will need to make subsidiary factual findings about that extrinsic evidence. These are the ‘evidentiary underpinnings' of claim construction that we discussed in Markman, and this subsidiary factfinding must be reviewed for clear error on appeal.” Id. (citing 517 U.S. 370).

         To ascertain the meaning of claims, courts look to three primary sources: the claims, the specification, and the prosecution history. Markman, 52 F.3d at 979. The specification must contain a written description of the invention that enables one of ordinary skill in the art to make and use the invention. Id. A patent's claims must be read in view of the specification, of which they are a part. Id. For claim construction purposes, the description may act as a sort of dictionary, which explains the invention and may define terms used in the claims. Id. “One purpose for examining the specification is to determine if the patentee has limited the scope of the claims.” Watts v. XL Sys., Inc., 232 F.3d 877, 882 (Fed. Cir. 2000).

         Nonetheless, it is the function of the claims, not the specification, to set forth the limits of the patentee's invention. Otherwise, there would be no need for claims. SRI Int'l v. Matsushita Elec. Corp., 775 F.2d 1107, 1121 (Fed. Cir. 1985) (en banc). The patentee is free to be his own lexicographer, but any special definition given to a word must be clearly set forth in the specification. Intellicall, Inc. v. Phonometrics, Inc., 952 F.2d 1384, 1388 (Fed. Cir. 1992). Although the specification may indicate that certain embodiments are preferred, particular embodiments appearing in the specification will not be read into the claims when the claim language is broader than the embodiments. Electro Med. Sys., S.A. v. Cooper Life Sciences, Inc., 34 F.3d 1048, 1054 (Fed. Cir. 1994).

         This Court's claim construction analysis is substantially guided by the Federal Circuit's decision in Phillips v. AWH Corporation, 415 F.3d 1303 (Fed. Cir. 2005) (en banc). In Phillips, the court set forth several guideposts that courts should follow when construing claims. In particular, the court reiterated that “the claims of a patent define the invention to which the patentee is entitled the right to exclude.” Id. at 1312 (quoting Innova/Pure Water, Inc. v. Safari Water Filtration Sys., Inc., 381 F.3d 1111, 1115 (Fed. Cir. 2004)). To that end, the words used in a claim are generally given their ordinary and customary meaning. Id. The ordinary and customary meaning of a claim term “is the meaning that the term would have to a person of ordinary skill in the art in question at the time of the invention, i.e., as of the effective filing date of the patent application.” Id. at 1313. This principle of patent law flows naturally from the recognition that inventors are usually persons who are skilled in the field of the invention and that patents are addressed to, and intended to be read by, others skilled in the particular art. Id.

         Despite the importance of claim terms, Phillips made clear that “the person of ordinary skill in the art is deemed to read the claim term not only in the context of the particular claim in which the disputed term appears, but in the context of the entire patent, including the specification.” Id. Although the claims themselves may provide guidance as to the meaning of particular terms, those terms are part of “a fully integrated written instrument.” Id. at 1315 (quoting Markman, 52 F.3d at 978). Thus, the Phillips court emphasized the specification as being the primary basis for construing the claims. Id. at 1314-17. As the Supreme Court stated long ago, “in case of doubt or ambiguity it is proper in all cases to refer back to the descriptive portions of the specification to aid in solving the doubt or in ascertaining the true intent and meaning of the language employed in the claims.” Bates v. Coe, 98 U.S. 31, 38 (1878). In addressing the role of the specification, the Phillips court quoted with approval its earlier observations from Renishaw PLC v. Marposs Societa' per Azioni, 158 F.3d 1243, 1250 (Fed. Cir. 1998):

Ultimately, the interpretation to be given a term can only be determined and confirmed with a full understanding of what the inventors actually invented and intended to envelop with the claim. The construction that stays true to the claim language and most naturally aligns with the patent's description of the invention will be, in the end, the correct construction.

Phillips, 415 F.3d at 1316. Consequently, Phillips emphasized the important role the specification plays in the claim construction process.

         The prosecution history also continues to play an important role in claim interpretation. Like the specification, the prosecution history helps to demonstrate how the inventor and the United States Patent and Trademark Office (“PTO”) understood the patent. Id. at 1317. Because the file history, however, “represents an ongoing negotiation between the PTO and the applicant, ” it may lack the clarity of the specification and thus be less useful in claim construction proceedings. Id. Nevertheless, the prosecution history is intrinsic evidence that is relevant to the determination of how the inventor understood the invention and whether the inventor limited the invention during prosecution by narrowing the scope of the claims. Id.; see Microsoft Corp. v. Multi-Tech Sys., Inc., 357 F.3d 1340, 1350 (Fed. Cir. 2004) (noting that “a patentee's statements during prosecution, whether relied on by the examiner or not, are relevant to claim interpretation”).

         Phillips rejected any claim construction approach that sacrificed the intrinsic record in favor of extrinsic evidence, such as dictionary definitions or expert testimony. The en banc court condemned the suggestion made by Texas Digital Systems, Inc. v. Telegenix, Inc., 308 F.3d 1193 (Fed. Cir. 2002), that a court should discern the ordinary meaning of the claim terms (through dictionaries or otherwise) before resorting to the specification for certain limited purposes. Phillips, 415 F.3d at 1319-24. According to Phillips, reliance on dictionary definitions at the expense of the specification had the effect of “focus[ing] the inquiry on the abstract meaning of words rather than on the meaning of claim terms within the context of the patent.” Id. at 1321. Phillips emphasized that the patent system is based on the proposition that the claims cover only the invented subject matter. Id.

         Phillips does not preclude all uses of dictionaries in claim construction proceedings. Instead, the court assigned dictionaries a role subordinate to the intrinsic record. In doing so, the court emphasized that claim construction issues are not resolved by any magic formula. The court did not impose any particular sequence of steps for a court to follow when it considers disputed claim language. Id. at 1323-25. Rather, Phillips held that a court must attach the appropriate weight to the intrinsic sources offered in support of a proposed claim construction, bearing in mind the general rule that the claims measure the scope of the patent grant.

         The Supreme Court of the United States has “read [35 U.S.C.] § 112, ¶ 2 to require that a patent's claims, viewed in light of the specification and prosecution history, inform those skilled in the art about the scope of the invention with reasonable certainty.” Nautilus, Inc. v. Biosig Instruments, Inc., 134 S.Ct. 2120, 2129 (2014). “A determination of claim indefiniteness is a legal conclusion that is drawn from the court's performance of its duty as the construer of patent claims.” Datamize, LLC v. Plumtree Software, Inc., 417 F.3d 1342, 1347 (Fed. Cir. 2005) (citations and internal quotation marks omitted), abrogated on other grounds by Nautilus, 134 S.Ct. 2120.

         III. AGREED TERMS

         In their August 10, 2017 Joint Claim Construction Chart and Prehearing Statement (Dkt. No. 145, at 2-3) and their October 18, 2017 Joint Claim Construction Chart (Dkt. No. 168, Ex. A), the parties have set forth agreements as to the following terms in the patents-in-suit:

Term

Agreement

“means for transporting the optical signal”

('055 Patent)

This claim term is governed by 35 U.S.C.

§112(6).

Function: “transporting the optical signal”

Corresponding Structure Disclosed in the Specification: optical fiber (2:39-41); optical fiber 20 (Fig. 1, 4:35-38, 4:54-55).

“the optical signals”

('511 Patent, Claims 1, 9)

“the optical signal transmitted by the transmitter

“the phase-modulated optical signals”

('511 Patent, Claim 9)

“the phase-modulated optical signal transmitted by the transmitter”

“an electric signal”

('511 Patent, Claims 1, 9)

“an electrical signal”

“the electrical signal”

('511 Patent, Claims 1, 9)

“an electric signal” is the antecedent basis for the term “the electrical signal”

“the electrical signal after filtering”

('511 Patent, Claims 2, 10)

“the filtered electrical signal”

“the electrical signal after scaling is compared”

('511 Patent, Claims 5, 13)

“the filtered and scaled electrical signal”

“filtering the electrical signal to produce an

average optical power”

('511 Patent, Claims 1, 9)

“filtering the electrical signal from the photodetector to provide the average optical power of the optical signals”

“the second optical signal”

('898 Patent, Claims 1, 4, 9, 14, 18, 23)

“a second optical signal” is antecedent for “the second optical signal”

         IV. DISPUTED TERMS

         A. “phase modulate”

Plaintiff's Proposed Construction

Defendants' Proposed Construction

“alter the phase of light to create an optical signal having a phase that is representative of data”[1]

“alter the phase of light while keeping the amplitude of the light constant to create an optical signal having a phase that is representative of data”

(Dkt. No. 157, at 8; Dkt. No. 165, at 10; Dkt. No. 168, Ex. B, at 1-2, 9, 15, 21, 23, 25, 31 & 35.) The parties submit that “phase modulate, ” and similar terms, appear in Claims 1, 9, and 11 of the '012 Patent, Claims 1 and 27 of the '055 Patent, Claims 3, 14, 16, and 25 of the '327 Patent, Claim 9 of the '511 Patent, Claims 1, 5, 10, 13, and 14 of the '592 Patent, Claims 1, 4, 7, 12, and 19 of the '816 Patent, Claims 3, 4, 17, and 18 of the '898 Patent, and Claims 1, 4, 5, and 12- 14 of the '952 Patent. (See Dkt. No. 168, Ex. B.)

         (1) The Parties' Positions

         Plaintiff argues that Defendants' proposal of “keeping the amplitude of the light constant” should be rejected because “the claims make clear that the amplitude can change during phase modulation.” (Dkt. No. 157, at 9.) Plaintiff also argues that disclosures in the specifications demonstrate that “the patents explicitly contemplate changing the amplitude as well as the phase of the light.” (Id., at 10.)

         Defendants respond that “Defendants' construction is the plain meaning in the context of the patents at the time of the invention, as confirmed by evidence cited by Plaintiff.” (Dkt. No. 165, at 10.) Defendants also argue that “the specifications uniformly and exclusively refer to the amplitude of the light as constant during phase modulation; they tout the benefits of that characteristic to the invention; they disparage prior art, like the '615 patent, that combine both amplitude and phase variations and call such a system an ‘amplitude modulation system'; and they never refer to the invention as combining amplitude and phase modulation, much less call such a combination ‘phase modulation.'” (Id., at 16-17.) For example, Defendants argue that “[i]f the signal's amplitude were to vary with the data, that would frustrate the object of the invention of providing a secure phase modulated optical data transmission.” (Id., at 13.)

         Plaintiff replies by emphasizing claim differentiation as to dependent Claim 6 of the '816 Patent. (Dkt. No. 167, at 5.)

         At the November 20, 2017 hearing, the parties presented oral arguments as to this disputed term. (See Dkt. No. 181, Joint Notice Regarding the Markman Hearing, at 1.)

         (2) Analysis

         Claims 1 and 6 of the '816 Patent, for example, recite (emphasis added):

1. A fiber optic data transmission system comprising:
a transmitter having a laser emitting a continuous wave light,
a phase modulator phase modulating the continuous wave light as a function of an electronic input data stream and of an electronic feedback loop with a feedback time delay, the electronic feedback loop being fed back to the electronic input data stream, so as to create an optical signal bearing information in phase-modulated form, and
a telecommunications optical fiber connected to at least one receiver, the phase-modulator being connected to the telecommunications fiber so that the phase-modulated information optical signal is transmitted over the telecomm[]unications fiber without recombining with the continuous wave light, the receiver including an interferometer having a first fiber arm and a second fiber arm and having an interferometric delay being a function of the feedback time delay.
* * *
6. The system as recited in claim 1 wherein an amplitude of the phase-modulated optical signal is constant.

         The doctrine of claim differentiation thus weighs against Defendants' proposal that a “phase modulated” signal must have constant amplitude. See, e.g., Liebel-Flarsheim Co. v. Medrad, Inc., 348 F.3d 898, 910 (Fed. Cir. 2004) (“[W]here the limitation that is sought to be ‘read into' an independent claim already appears in a dependent claim, the doctrine of claim differentiation is at its strongest.”); Wenger Mfg., Inc. v. Coating Mach. Sys., Inc., 239 F.3d 1225, 1233 (Fed. Cir. 2001) (“Claim differentiation, while often argued to be controlling when it does not apply, is clearly applicable when there is a dispute over whether a limitation found in a dependent claim should be read into an independent claim, and that limitation is the only meaningful difference between the two claims.”).

         Plaintiff has also cited Claim 14 of the '327 Patent, which recites an energy level detector including a threshold “indicating a drop in amplitude of a phase-modulated signal.” Plaintiff argues that this claim would be non-sensical under Defendants' proposed construction. Plaintiff's argument is unavailing, however, in light of disclosure that detecting a drop in amplitude can be useful in the context of a signal that normally has constant amplitude. See '327 Patent at 4:43-47 (“The phase-modulated signals have the advantage that breach detection by the energy level detector work [sic] more effectively, since the amplitude of the optical signal is constant and thus a drop in the optical signal level is more easily detected.”).

         Also of note, Claim 5 of the '592 Patent appears to present a choice of either amplitude modulation or phase modulation (emphasis added):

5. The card as recited in claim 4 further comprising a switch for switching between an amplitude-modulated mode and a phase-modulated mode.

See '898 Patent at 4:44-45 (“The transceiver of the present invention preferably operates in a phase-modulated mode . . . .”) (emphasis added). This recital of “switching between” appears to imply a selection, at any given time, of either one or the other (not both at the same time).

         Plaintiffs have further pointed out that Claims 1, 15, 17, and 27 of the '055 Patent, all of which are independent claims, already expressly recite phase-modulated optical signals that are “free of amplitude modulation as a function of the input electronic data stream.” Given that the parties have proposed constructions for “‘phase modulate' and grammatical variations” (Dkt. No. 157, at 8) across all of the patents-in-suit (presumably for the sake of simplicity and efficiency, which are commendable objectives), any redundancy that may arise in certain claims as a result of proceeding in this fashion does not warrant rejecting a construction. See 01 Communique Lab., Inc. v. LogMeIn, Inc., 687 F.3d 1292, 1296 (Fed. Cir. 2012) (noting absence of “any authority for the proposition that construction of a particular claim term may not incorporate claim language circumscribing the meaning of the term”).

         Turning to the specifications, the patentee disclosed that “[c]ontroller 18 is also programmable to control the optical power output of the light emitted by laser 12” ('816 Patent at 3:66-67), which Plaintiff's expert opines amounts to a disclosure of changing amplitude. (Dkt. No. 157-22, Sept. 15, 2017 Lebby Decl., at ¶ 29.) Read in context, however, this disclosure refers not to amplitude modulation but rather to an ability to minimize transmission power:

Light emitted from laser 12 is depolarized by a depolarizer 14 and passes through a phase modulator 16, for example a Mach-Zender phase modulator. An electronic controller 18, for example a PLC, controls phase modulator 16. Controller 18 is also programmable to control the optical power output of light emitted by laser 12. Preferably, the power output is set as low as possible for a given optical span, while maintaining a low bit error rate. This reduces the light available for any tap.

'816 Patent at 3:62-4:3 (emphasis added).

         Likewise, although Plaintiff cites disclosure in the '898 Patent regarding amplitude modulation, this disclosure expressly distinguishes phase modulation from amplitude modulation, explaining that constant amplitude is an “advantage” of “phase-modulated signals”:

The transceiver of the present invention preferably operates in a phase-modulated mode, though conventional amplitude-modulated transmitters and receivers, including those using return-to-zero type signals, for example, may also be used. The phase-modulated signals have the advantage that breach detection by the energy level detector work[s] more effectively, since the amplitude of the optical signal is constant and thus a drop in the optical signal level is more easily detected.

'898 Patent at 4:44-52 (emphasis added). The '816 Patent likewise contrasts phase modulation and amplitude modulation:

By sending the data in phase-modulated form, as opposed to amplitude modulated form, the data is [sic] must be read by an interferometer receiver. The use of such a receiver is easy to detect.

'816 Patent at 3:20-23 (emphasis added).

         Plaintiff properly submits that courts generally “do not import limitations into claims from examples or embodiments appearing only in a patent's written description, even when a specification describes very specific embodiments of the invention or even describes only a single embodiment, unless the specification makes clear that the patentee . . . intends for the claims and the embodiments in the specification to be strictly coextensive.” JVW Enters., Inc. v. Interact Accessories, Inc., 424 F.3d 1324, 1335 (Fed. Cir. 2005) (citation and internal quotation marks omitted).

         Here, however, the specifications disparage amplitude-modulated optical signals as being easily tapped. For example, the '816 Patent discloses:

Amplitude-modulated optical signals, with their ease of detection from a photodiode, require that only a small amount of energy be tapped and passed through the photodiode in order to be converted into a tapped electronic data stream.
* * *
U.S. Pat. No. 6, 072, 615 purports to describe a method for generating return-to-zero optical pulses using a phase modulator and optical filter. The RZ-pulse optical signal transmitted over the fiber is easily readable by a detector. The system is an amplitude-modulated system.
U.S. Pat. No. 5, 606, 446 purports to describe an optical telecommunications system employing multiple phase-compensated optical signals. Multiple interferometric systems are combined for the purpose of multiplexing various payloads on the same optical transmission path. The patent attempts to describe a method for providing fiber usage diversity using optical coherence length properties and a complex transmit/receive system. Each transmitter has a splitter, a plurality of fibers and a plurality of phase modulators to create the multiplexed signal, which is then demultiplexed at the receiver. This system is complex and expensive. Moreover, each phase-modulated light path is combined with a continuous wavelength base laser light path when sent over a telecommunications line, so that amplitude-modulated signals result.
As with U.S. Pat. No. 5, 606, 446, U.S. Pat. No 5, 726, 784 discloses creating an amplitude-modulated data stream by combining a phase-modulated light path with a continuous wave base laser light path.

'816 Patent at 1:38-43 & 2:16-39 (emphasis added).

         The “present invention, ” by contrast, uses a signal that can be received only with an appropriate interferometer:

With the system of the present invention, the receiver functions as an interferometer. An attempt to read the optical signal in the fiber, for example from a tap, requires knowledge of the delay and the creation of a precise physical delay path in the interferometer.

Id. at 2:48-53. Again, the patentee's disclosures contrast phase modulation and amplitude modulation:

The present invention thus permits a card-based phase modulated transmission system, which can provide for more secure data transmission than existing amplitude-based cards.
* * *
Because the transmitter is typically transmitting in secure mode using a continuous wave laser, the energy level read by the detector should be constant. When a drop in the energy level is detected, which may indicate a tap, the card may provide an alarm signal . . . .

'592 Patent at 2:41-44 & 2:64-3:2.

         “To find disavowal of claim scope through disparagement of a particular feature, we ask whether the specification goes well beyond expressing the patentee's preference . . . [such that] its repeated derogatory statements about [a particular embodiment] reasonably may be viewed as a disavowal.” Openwave Sys., Inc. v. Apple Inc., 808 F.3d 509, 513 (Fed. Cir. 2015) (citations and internal quotation marks omitted); see Id. at 517 (“There is no doubt a high bar to finding disavowal of claim scope through disparagement of the prior art in the specification.”).

         As a general matter, Defendants have not shown that phase modulation and amplitude modulation are necessarily mutually exclusive. In other words, Defendants have not shown that using phase modulation necessarily precludes using amplitude modulation. (See Dkt. No. 157-22, Sept. 15, 2017 Lebby Decl., at ¶ 27; see also Dkt. No. 157, Ex. 9, Fiber Optics Standard Dictionary 742 (3d ed. 1997) (“phase modulation: Angle modulation in which the phase angle of a carrier, such as an electronic, radio, or optical carrier, is caused to depart from its reference value by an amount proportional to the instantaneous value of the modulating signal.”); id., Ex. 10, The Authoritative Dictionary of IEEE Standards Terms 816 (7th ed. 2000) (similar).) Thus, although the evidence cited by Defendants confirms that a phase modulation limitation cannot be met by amplitude modulation, Defendants have not shown that using phase modulation necessarily precludes using amplitude modulation.

         Defendants have also cited a treatise that Plaintiff's expert has cited (Dkt. No. 157-22, Sept. 15, 2017 Lebby Decl., at ¶ 27), which states that “[i]n the case of PSK [(phase shift keying)] format, the optical bit stream is generated by modulating the phase . . . while the amplitude . . . [is] kept constant.” (Dkt. No. 165, Ex. J, Govind P. Agrawal, Fiber-Optic Communication Systems 246-47 (1997); id. at 14 (“PSK” is phase modulation “applied in the digital case”)). This is extrinsic evidence, however, and is therefore of somewhat limited weight. See Phillips, 415 F.3d at 1317 (“while extrinsic evidence can shed useful light on the relevant art, we have explained that it is less significant than the intrinsic record in determining the legally operative meaning of claim language”) (citations and internal quotations marks omitted).

         Nonetheless, the specification explains that the desired benefits of phase modulation are obtained only in the absence of amplitude modulation. See '898 Patent at 4:44-52 (quoted above). This comports with the patentee's above-quoted disparagement of prior art references that the patentee explained combined phase modulation with amplitude modulation, which the patentee disparaged as being “amplitude-modulated.” See '816 Patent at 2:32-35 (“each phase- modulated light path is combined with a continuous wavelength base laser light path when sent over a telecommunications line, so that amplitude-modulated signals result”); see also Id. at 2:36-39 (similar). Further, as to Plaintiff's claim differentiation arguments:

Although claim differentiation is a useful analytic tool, it cannot enlarge the meaning of a claim beyond that which is supported by the patent documents, or relieve any claim of limitations imposed by the prosecution history.

Fenner Investments, Ltd. v. Cellco P'ship, 778 F.3d 1320, 1327 (Fed. Cir. 2015).

         Thus, on balance, in light of the disparagement of prior art involving amplitude modulation, and in light of the disclosures of the advantages of using phase modulation instead of amplitude modulation, the “phase modulate” terms should be interpreted so as to exclude amplitude modulation.

         The Court therefore hereby construes “phase modulate” (and similar terms identified by the parties) to mean “alter the phase of light while keeping the amplitude of the light constant to create an optical signal having a phase that is representative of data.”

         B. “output for altering the phase of the phase modulator”

Plaintiff's Proposed Construction

Defendants' Proposed Construction

“converted signal used to alter the phase of light in the phase modulator” [2]

“converted signal used to modulate the phase of light in the phase modulator”

(Dkt. No. 157, at 11; Dkt. No. 165, at 31; Dkt. No. 168, Ex. B, at 35.) The parties submit that this term appears in Claim 1 of the '952 Patent. (See Dkt. No. 168, Ex. B.)

         (1) The Parties' Positions

         Plaintiff argues that “[t]he Court should reject Defendants' attempt to rewrite the claim with the narrower term ‘modulate' because there is no express definition or clear and unambiguous disclaimer that could justify replacing the plain and ordinary word ‘alter' in the claim, with a different term, as Defendants propose.” (Dkt. No. 157, at 11.) Plaintiff also argues that its proposal “is consistent with the specification.” (Id., at 12.)

         Defendants respond that “[t]he claim language and the specification confirm that the whole point of the invention is to use the output to modulate the light and not merely to alter some aspect of a phase unrelated to the phase modulation claimed.” (Dkt. No. 165, at 31.) Further, Defendants argue, “[t]he claim language also indicates there is no other alteration occurring.” (Id., at 32.)

         Plaintiff replies that “Defendants fail to point to any disclaimer or lexicography requiring such a narrowing construction.” (Dkt. No. 167, at 7.) Plaintiff also argues that “Defendants make attorney arguments, with no supporting evidence, that modulation is the only form of alteration that would work for the claimed invention, ” and Plaintiff submits that Defendants “have failed to rebut Dr. Lebby's expert testimony.” (Id.)

         At the November 20, 2017 hearing, the parties presented no oral arguments as to this disputed term. (See Dkt. No. 181, Joint Notice Regarding the Markman Hearing, at 1.)

         (2) Analysis

         Claim 1 of the '952 Patent recites (emphasis added):

1. A fiber optic data transmission system comprising:
a transmitter having a laser emitting a continuous wave light, the transmitter including a phase modulator phase modulating the continuous wave light and a control circuit controlling the phase modulator as a function of an electronic input data stream having a time delay, so as to create a phase-modulated optical signal;
an optical fiber transmitting the phase-modulated optical signal; and
a receiver, the receiver including an interferometer for receiving the phase-modulated optical signal, the interferometer having a first arm and a second arm, the second arm being longer than the first arm, the interferometer having an interferometric delay corresponding to the time delay and a phase difference imparted by the first and second arms, the control circuit imparting a phase to represent a binary zero or one as a function of the phase difference, the control circuit including a digital-to-analog converter having an output for altering the phase of the phase modulator.
The specification discloses:
Depending on the controller output, phase modulator 16 either imparts a certain phase shift to the non-information bearing light to represent a binary zero or another certain degree phase shift (for example 180 degrees different from the first certain phase shift) on the light passing through phase modulator 16 to represent a binary one, thus creating an optical signal 22, which represents a stream of binary bits.
* * *
D-A converter 234 provides a voltage output corresponding to the digital input A4, which then controls the phase modulator 16. The phase modulator 16 shifts the optical signal by an amount proportional to the voltage applied over a full 360-degree range.

'952 Patent at 5:25-31 & 8:33-35.

         Plaintiff argues that “just because a phase is ‘altered' does not necessarily mean it is ‘modulated.' Whether an alteration results in a modulation depends on whether the output corresponds to a stream of binary bits.” (Dkt. No. 157, at 12.) In other words, Plaintiff argues, the phase can be altered without necessarily encoding data or otherwise “modulating.”

         Defendants have emphasized that the claim recites “a control circuit controlling the phase modulator as a function of an electronic input data stream, ” arguing that the “output for altering the phase of the phase modulator” is therefore necessarily based on the data stream. (Dkt. No. 165, at 31-32; see '952 Patent at 8:31-34 (“D-A converter 234 provides a voltage output corresponding to the digital input A4, which then controls the phase modulator 16.”))

         On balance, the claim language cited by Defendants does not demonstrate that “altering” necessarily means “modulating, ” and no relevant disclaimer or definition is evident in the specification. On the contrary, the disclosure cited by Defendants appears to relate to “phase compensation” rather than to modulation. See '952 Patent at 8:3-54; see also Id. at 8:55-59 (“The transmitter 10 with compensation circuit 210 thus provides that the phase for each bit is rotated slightly, so that when the signals are passed through interferometer 40, a binary zero results in zero voltage and a binary one in a detectable voltage at photodetector 38.”) (emphasis added). The Court therefore hereby expressly rejects Defendants' proposed construction.

         The Court accordingly hereby construes “output for altering the phase of the phase modulator” to mean “converted signal used to alter the phase of light in the phase modulator.”

         C. “energy ...


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